The answer to that is... it could happen. See this. One of the debunkings of that claim that I've seen is that the "fact checkers" [1] couldn't find a $1 million transfer from the Obama campaign to Odinga, and that there's no such thing as the "Friends of Senator B.O." However, the wording at the first link implies that it wasn't a transfer so much as Obama facilitating donations from others directly to Odinga.

However, before you get too excited, see this email supposedly from Obama:

"I will kindly wish that all our correspondence [be] handled by Mr Mark Lippert. I have already instructed him. This will be for my own security both for now and in future."

You probably had the same reaction as I did: that doesn't sound like the BHO we know. In fact, it sounds more like someone who sends you an email wanting to establish a "mutually beneficial business relationship" in order to retrieve Thirty Three Million American Dollars.

Despite that, there are definitely links between BHO and Odinga, and it's pretty clear that - while he did speak with Odinga's opposition - he was in Odinga's corner.

However, the claim that the pact between Odinga and Muslim leaders promised Sharia law appears to be falsified [2].

[1] politifact.com/truth-o-meter/statements/465
[2] wikileaks.org/wiki/
Framing_Obama:_what_the_Spectator_and_the_New_York_Sun_won't_tell_you